System for supplying feed water to boilers



1941- J. w. SCHMID 2,251,426

SYSTEM FOR SUPPLYING FEED WATER 'ro BOILERS Filed March 8, 1940 5 Sh eets-Sheet l Q V B J01. IAN W SOP/MID .Aug. 5, 1941. J, w. SCHMID SYSTEM FOR SUPPLYING FEED WATER'TO BOILERS Filed March 8, 1-940 3 Sheets-Sheet 2 ul. m/v SCH/VHO Aug. 5, 1941. J. w. SCHMID SYSTEM FOR SUPPLYING FEED wmm T0 BOILERS s Shets-Sheet 5 Filed March 8, 1940 W SCffM/D y ll Ill 1 Patented Aug. 5, 1941 STAT E S FFCE SYSTEM F052. SUPPLYING FEED WATER T BOILERS 7 Claims.

This invention relates to steam boilers and more particularly to a means for preventing pitting within the boiler. This invention is a continuation-in-part of my copending application, Serial No. 253,665, for Prevention of pitting of steam boilers, filed January 30, 1939.

An object of this invention is to provide an improved system and means for discharging feed water into the boiler to thereby raise the pH of the feedwater within the boiler so as to substantially eliminate pitting.

Another object of this invention is to provide a system-and means for discharging feed water into a boiler whereby the feed water is mixed with a greater portion of boiler water before the feed water is finally discharged into the boiler, and at the same time the temperature of the feed water is raised through commingling with the boiler water.

Under recognized principles of water treatment for boiler use there is an excess of alkalinity over hardness or scale forming salts. When the Water is properly treated, the hardness that remains in the feed water is precipitated in the boiler in the form of a soft sludge that does not adhereto the boiler parts and does not form scales. The excess alkalinity concentrates in the boiler and at the higher temperature inside the boiler part of the carbonate excess is converted into caustic soda. In a boiler carrying 200 lbs. gauge pressure, this carbonate excess continues until '75 or 80% is caustic soda and or is sodium carbonate. While it is possible to treat water for boiler use and raise its pH value above the pitting point before it enters the boiler, thus preventing pitting, this is not always practical or even desirable, as when water with low hardness anddissolved solids and low pH is treated with enough chemical to correct the low pH before it enters the boiler, the concentration inside the boiler increases to a point where it interferes with the proper operation of the boiler, causing foamingand danger of caustic embrittlement of the boiler parts. With this invention only a moderate excess of alkalinity over hardness is main- 1 tained in the feed water, and the pH is raised above the pitting point by mixing it-with the boiler water containing caustic soda. This is done by the CO2, and the C02 liberated by the decomposition of bicarbonates in the feedwater readily combines in the pipe and trough of this device with the caustic soda of the boiler water forming normal sodium carbonate. This normal carbonate is discharged from the trough into the boiler where it is slowly converted until or is caustic soda. Any dissolved oxygen that may be {in the feed water is 'drivenolf in the trough and is carried from the boiler with the steam. In the ordinary method of putting feed water into a boiler, especially where there is a small amount of circulation of water in the boiler, as in the case of a locomotive when itisstanding still and the pH of the feed water is below the pittin point, the .mixture of the feed Water in the boiler water is not sufficient to prevent pitting without using excessive treatment. This is shown by the fact that when there is pitting in a boiler most of it is near the point where the feed water enters the boiler and in the path and direction of circulationof the feed water after it enters the boiler. As the feed water mixes with the boiler water, the pH is raised and the pitting diminishes. This invention by thoroughly mixing the boiler water with the feed water uses the caustic soda of the boiler water to raise the pH of the resulting mixture above pitting point be fore it comes in contact-with the metal parts of the boiler.

A still further object of this invention is to provide a system and means which will greatly reduce foaming. This will result from the calcium and .magnesiumof the incoming feed water being precipitated as calcium carbonate and magnesium hydroxide more rapidly and completely by the higher pH value of the mixture and in the presence of recirculated sludge, already in the boilerwater so that a better floc is obtained. Also the nearly uniform mixture of chemical compounds throughout the boiler and the uniform temperature of the boiler water will allow a higher'concentration of dissolved solids in the water thus causing less foaming.

A further object of this invention is to provide a system and means whereby the dissolved oxygen and the 002 may be discharged into the steam above the water level so that the oxygen and the CO2 gas may be taken from the boiler with the steam.

To the foregoing objects and to others which may hereinafter appear, the invention consists of the novel constructions, combination and arrangement of parts as will be more specifically referred to and illustrated in the accompanying drawings wherein is shown an embodiment of the invention, but it is to be understood that changes, variations andmodifications may be resorted to which fall within the scope of the invention as laim In the drawings:

Figure 1 is a fragmentary horizontal sectional view of a boiler structure having a device constructed according to an embodiment of this invention mounted therein. v

Figure 2 is a similar View by showing a modified form of structure to prevent the pitting in the boiler.

Figure 3 is a fragmentary vertical section of a boiler embodying another modification of this invention.

Figure 4 is a fragmentary sectional view taken on the line 44 of Figure 3.

Figure 5 is an enlarged sectional view taken on the line 55 of Figure 4.

Figure 6 is a top plan partly in section of the structure shown in Figure 5.

Figure 7 is a sectional view taken on the line 'l---! of Figure 6.

Figure 8 is a sectional view taken on the line 8-8 of Figure 6.

Figure 9 is a sectional View taken on the line 99 of Figure 6.

Referring to the drawings and first to Figure l, the character B designates generally a boiler structure having a fire box IE1 at one end and a plurality of tubes H which are connected at one end to the fire box and which communicate at opposite ends with the usual smoke box.

in order to provide a means whereby the incoining feed water may be mixed with boiler waterprior to the discharge of the feed water into the boiler, I have provided a trough generally designated as I2 which is positioned within the boiler B at a point above the uppermost of the tubes I I and with the lower portion of the trough l2 disposed slightly above the uppermost of the tubes II. In other words, the trough I2 is partly disposed within the boiler water and a portion of the trough l2 projects upwardly above the normal water level. This water level is slightly above the top of the crown sheet which is positioned above the fire box 10. The trough [2 comprises a bottom wall M which is provided with a plurality of longitudinally spaced apart openings or holes I3. The specific construction of the trough I2 is more clearly shown in my copending application, Serial No. 253,665. The trough I2 is open at each end and at a point between the ends thereof the trough i2 is provided with opposed and inwardly projecting bypass members l5. These by-pass members 55 are disposed in rearwardly convergent relation and are adapted to by-pass a quantity of the water in the trough into the boiler water. In this manner the entire amount of feed water moving lengthwise of the trough l2 will not be discharged over or beyond the forward or discharge end IQ of the trough l2.

A discharge nozzle I1 is positioned within the boiler B and extends partly into the intake end l8 of the trough I2. The discharge nozzle I! is adapted to discharge the incoming feedwater and a quantity of boiler water, as will be hereinafter described in the trough l2 so that the mixture of feed and boiler water will move lengthwise of the trough !Z in the same direction as the circulation of boiler water within the boiler B. 1

The nozzle I! is connected to a pipe H) which extends through a wall 29 of the boiler B and the pipe 19 is connected at its outer end to a coupling 2!. A pipe 22 is connected to the coupling El and a rearwardly closing check valve 23 is interposed in the pipe 22. A feed water pipe 24 is connected at its forward end. to

an enlarged pipe 25 which is connected to the pipe 23. Preferably the feed pipe 24 is constructed in the form of a nozzle which is dis-' posed within the pipe 25 so that when the feed water is discharged from the pipe 24 into the pipe 25 a suction will be formed in the pipe 25. A boiler water pipe 26 is connected at one end to the pipe 25 at a point exteriorly of the boiler B, thepipe 26 beingcorinected to the pipe 25 by a coupling 27. The inner end of the boiler water pipe 26 terminates in a downwardly opening suction head 28 which is adapted to be dis-- posed slightly below the normal water level in the boiler B so that the suction formed in the outer pipe 25 will cause the boiler water to be drawn inwardly through the head 28, throughthe pipe .26 and then be mixed withthe feed water in the mixing pipe or tube 25 The rearwardly closing check valve 23 will prevent any water beyond the check valve to flow rearwardly thereof through the pipe 22.

Referring now to Figure 2, the numeral 29 des ignates generally a boiler structure similar to that shown in Figure l and the numeral 30 des-- ignates a trough which is positioned within the boiler 29, the details of the trough 30 being similar to the details of the trough l2. A nozzle 31 extends into the intake end 32 of the trough 30 and is adapted to discharge a mixture of boiler and feed water into the trough 30 so that the' direction of movement of the incoming water in the trough 33 will be the same as the direction of circulation of the boiler water in the boiler 29. The trough 3D is provided with by-pass members 33 forwardly of the rear end 32 thereof and a plurality of bottom openings 34 are provided in the bottom wall 35 of the trough 39. This trough 30 has the lower portion thereof projecting into the boiler water and the open upper portion thereof extends above the normal water level. In this manner any dissolved oxygen or CO2 gas rising from the water in the trough 39 will be mixed or commingled with the steam so that this dissolved oxygen and CO2 gas will be carried out of the boiler with the steam. The nozzle 35 is connected to a pipe 36 which extends through a wall 3'! of the boiler 29 and a check valve 38 is connected to the pipe 36 exteriorly of the Wall 3?. The check valve 38 is a rearwardly or outwardly closing valve so that the pressure within the boiler 28 will not cause the water in the pipe 35 to flow outwardly.

A feed water pipe 39 is connected to a T-coupling it which is connected at one side to the pipe 35 outwardly of the valve 33. A boiler water pipe comprising pipe sections 4! and 2 is connected to the coupling 4% and the two pipe sections il and 52 are connected to pump 43. The pump a3 is adapted to be operated in any suitable manner and is adapted to force boiler water to flow through the pipe sections 42 and Al to the coupling All in which the boiler water is mixed with the incoming feed water from the pipe 35. he pipe section 42 extends inwardly through the wall it? above the uppermost of the tubes i l in the boiler 29 and the pipe 42 ter minates at its inner end in a downwardly directed suction head 45. The suction head is positioned closely adjacent the forward wall 45 of the fire box 4? and terminates slightly below the normal water level so that when the pump 43 is operated the boiler water will be withdrawn through the suction head 45 and discharged into the coupling it} where the boiler water is mixed with. the incoming feed water and" forced tinwardly through the mixing pipe :36 and "discharged "fromthe nozzle '31 into. the trough 3E1.

By-iusing a pump 4361a'ny. desired proportion of boiler water: may "be 'withdrawn'from the boiler 29' fon'inixture with thefinc'oming feed water. In this. mannerthe'inoming feed water will'be heated-bytheboiler water to the desired degree' so that'whenthe combined mixture of boiler and feed water is dis'ch'argedinto"thetrough numeral 48 designates generally a conventional boiler structure embodying an outer shell or 'wall 49, a fire box 50 atone. end'thereof and asmoke box at the other end. A crown" sheet 52 is positioned over the top of the fire box '50 and a plurality of tubes'53 communicat'efthe fire box 56 with the smoke box 5 I. The'dot 'and dash line indicated by, the numeral 54 designates the normalwater level of the water in the boiler 48, 7

A trough or mixing member 55 is disposed withinthe boiler'4'8 and comprises an elongated tubular body 5 6 which as shown in Figure 4 is flared forwardly and is provided in its upper side with a V'-shaped or flared'opening 51. As shown in Figures 8 and 9, the tubular member 56 is gradually spread out so that at the'forward end thereof the tubular memberl56 assumes the configuration of x a U having a substantially fiat bottom wall 58 and vertical side walls 59. The forward end of the tubular memberf56 has a rearwardly reducing extension 60 which may be formed integrally therewith and which forms a substantial Venturi tube. This Venturi member 66 is preferably formed with an upwardly inclined lower wall 6| as shown in Figures 3 and 5 and a substantially horizontal upper wall 62. A funnelshaped or frusto conical intake member63 is connected at its apex to the reduced rear end of the mixing member 60 and this funnel-shaped member 63 has only a very slight portionthereof projecting above the water level .54 as shown more clearly in Figure'5. x

A secondmixingtube 64 is disposed rearwardly of the intake mernber63 and is of asubstantially smaller diametergthan'the rear diameter of the intake member 63 The mixing tube 64 at its forwardend is provided with a reduced nozzle 65 which is positioned within the intake member 63 as shown in'Figures4and'5. The rear end of the mixing tube6 4 is provided with a reduced portion 66 which merges into a rearwardly flared portion 61 forminganintakemouth. The intake. mouth or member 61 and the reducedportion 66 form a rear Venturi tubeanda feed water discharge nozzle 68 is disposedaxially of the, intake member 61. The nozzle68" is disposed within an intake tube '69 which extends rearwarollyv of and communicateswith'thej intake member 61. The rear end of the intake tube 69 terminates at a. po'int'closely adjacentthe forward wall III of the fire box 56 and this intake tube 69 is positioned substantially entirely below the normal water level 54. An intake feed pipe H is connected to the nozzle 68 and at right angles to the intake tube 69. A check valve 12 is connected to the pipe H e'xteriorly of the top wall 49 of the boiler 48 and the feed pipe H is adapted to be con- .nected tora suitable source of feed water supply. The forward mixing member 55 is supported within the boiler 48 by means of a plurality of bracketsor suspending bars "and" which are secured to the boiler wall 49 and to the mixing member "55. The mixing tube 64 and the intake tube "69 are supported horizontally in the boiler .48 by meansiof depending brackets or bars 15 and "16, respectively.

During the normal operation of the boiler 48, the water circulates from the crown sheet 52 forwardly'inthezdirection ofthe'smoke box 5| The feed and boiler "water mixing structure hereinbefore "described is'disposed horizontally within the boil'er' 43 with the intake end thereof rearmost so that the operation of the hereinbefore cl escribedflmixing structure will-act as a means to accelerate the circulation of the water within the boiler 46.

In thense'and operation where the structure shown in Figure "1 'is used, the forced the incoming feedwaterthrough the feed water pipe 24 'whichis. discharged into the mixing pipe or member '25 will forma suction in this mixing pipe 2 5: and thereby draw boiler water from the suc- 'tion'h'ea'd 23 through the'boiler water pipe '26. The boiler water from the pipe 26 will bemixed with th'efeed. water in the mixing. member 25 so thatthe temperature of the feed water will be raised in proportion to the quantity of boiler water which'is drawn from the boiler B. After the mixture ofboiler and feed water passes the checkvalve 23,'itwill pass through the pipe l9 and 'will have thetemperature thereof raised through the contact with the pipe I!) which is positioned within the boiler B. The mixture of boiler and feed water willthen be discharged from thenozzle' H in the same direction as the normalflow or circulation of boiler water in the boilerB. After the mixture of boiler and feed water has been discharged from the nozzle H, the current set-up in the trough l2 will draw in additionalboiler waterfthrough theintake end IQ of the trough I2 "and "the temperature thereof will be raised 'by'thesteam enteringthetrough through openings i3. This entire mixture will pass longitudinally and forwardly through the trough 'li2,'a portion of this complete mixture being "withdrawn-or by-passed by means of the vanes 'or by-p'assing members l5 which are carried by the vertical walls of the trough l2. After this mixture 'passes the outlet or discharge end l6 of the trough l2, it will commingle with the remaining boiler water. Any dissolved oxygen or CO2 caused by mixture of the feed water with the boiler water will rise from the trough l2 and any CO2 gas generated in the trough l2 will also rise and commingle with the steam above the trough l2. V

V The structure shown in Figure 2 operates in a somewhat similar manner to that shown in Figure lexcept that the quantity of boiler water which is mixed "with the feed Water may be controlled to the desired extent by controlling the operation of the pump 43 whichwithdraws boiler water from the boiler 29 andfol'ces this water into the coupling 40 and the mixing pipe 36.

The structure shown in Figures 3 to 9, inclusive, operates somewhat similar to that shown in Figure 1. However, the feed water is discharged under pressure from the discharge nozzle 68 into the Venturi structure formed by the oppositely flared portions 61 and 66. This structure will form a suction in the intake pipe 69 so as to force boiler water to move inwardly of the intake tube 69. This boiler water will be mixed with the feed water discharged from the nozzle 68. By providing the forwardly flared portion 66 the feed water will more thoroughly mix with the boiler water and by providing a second reduced end 65 at the forward end of the mixing tube 64, the velocity of the mixture of boiler and feed water is again increased so that a second suction will be formed at the discharge end of the nozzle 65. This suction will draw in additional boiler water through the rearwardly flared intake member 63 which will enter the mixing tube 55 from the forwardly flared member 60. The mixture of boiler and feed water will then move longitudinally of the mixing member 56 and any dissolved oxygen or CO2 gas in the mixture which is moving longitudinally through the tube 56 will be discharged through the opening 51 and thus be mixed with the steam which is partially present in the upper portion of the mixing member 56. This steam is present by reason of the fact that the upper portion of the mixing member 56 and the upper portion of the tube members 6!! and B3 are also slightly above the normal water level. By providing the several nozzles in the mixing structure hereinbefore described, the velocity of the incoming feed water which is mixed with the boiler water is such as to draw in a greater portion of boiler water than is possible with a structure such as that shown in Figure 1. The direction of movement of the incoming feed water through the mixing structure hereinbefore described is in the same direction as the normal direction of circulation of the boiler water so that the incoming feed water will accclerate'rather than retard the circulation of water in the boiler. Furthermore, by providing the intake member E3 forwardly of the mixing member 64, a quantity of sludge is also drawn into the mixing member 56.

What I claim is:

1. In a boiler, an upwardly opening trough open at each end, means supporting the trough in the boiler, a pipe discharging into one end of said trough, the opposite end of said pipe being open and positioned within the boiler below the normal water level, a pump interposed in said pipe, and means discharging feed water into said pipe between said pump and the discharge end of said pipe.

2. In a boiler, an upwardly opening trough open at each end and provided with a plurality of openings in the bottom thereof, a feed pipe discharging into one end of said trough, suction means connected to said pipe and communicating with the boiler water for withdrawing boiler water from the boiler and mixing the boiler water with the feed water in said feed pipe, and means between the ends of said trough for discharging a portion of the Water therein into the boiler water.

3. In a boiler, an upwardly opening trough open at each end, means supporting the trough in the boiler, a feed pipe discharging into one end of said trough, and suction means connected to said pipe for withdrawing boiler water from the boiler and mixing the boiler Water with the feed water in said feed pipe.

4. In a boiler, a combined boiler water and feed water mixing structure comprising a trough positioned in the boiler and provided with open opposite end and an open top, a nozzle discharging into one end of said trough, a pipe connected at one end to said nozzle and extending laterally through a wall of the boiler, a coupling connected to said pipe, a feed water pipe connected to said coupling, a boiler water pipe connected to said coupling and extending interiorly of the boiler, a suction head carried by said boiler water pipe, and a pump interposed in said boiler water pipe whereby to control the quantity of boiler water withdrawn from the boiler for mixture with the feed Water.

5. In a boiler, an upwardly opening trough open at each end and communicating at each end with the boiler water, a combined boiler water and feed water mixing pipe discharging into one end of said trough, boiler water suction means communicating with said mixing pipe and said boiler for supplying boiler water to the mixing pipe, and a feed water supply means correlated with said mixing pipe for discharging feed water into said mixing pipe for simultaneous mixture of the feed water with the boiler water.

6. In a boiler, an open ended, upwardly opening horizontal trough positionable with at least a portion thereof below the normal boiler water level and communicating at each end thereof with the boiler water, a mixing pipe discharging into one end of said trough and extending laterally and outwardly of the boiler, a boiler water pipe having an open inner end disposed below the normal boiler water level and extending outwardly of the boiler, a tubular member connecting the extended ends of said mixing and boiler water pipes together, and means for discharging feed water into said tubular member whereby the discharge of feed water will draw boiler water into said tubular member for mix ture therein and subsequent discharge of the mixture into said trough, the discharge of the mixture into said trough also drawing additional boiler water into said one end of said trough.

'7. In a boiler, a combined boiler water and feed water mixing structure comprising a horizontally disposed trough-like mixing member open at each end and also open at the top thereof for the major portion of the length thereof, the open top portion of said member constituting a trough and the remaining portion constituting a mixing member communicating at one end with the trough and at the other end with the boiler water, means supporting said member with the open top portion thereof above the normal level of the boiler water, a second mixing member smaller in transverse section than said first mixing member and discharging at one end thereof into one end of said first mixing member, a boiler water conducting pipe extending axially from said second mixing member, a reduced con- I nection between said boiler water pipe and said second mixing member, a combined feed water discharge and suction nozzle correlated with and disposed axially of saidreduced connection, and a feed water pipe connected with said nozzle.

JULIAN W. SCHMID. 

